Horsemen is pretty obvious which deck you want.
Priest dominates with shadow word pains, shadow word death (after avenge proc). I even ran Crazed Alchemist + smite combos in there which killed one of the mobs. The more stuff you run for removal, the less luck dependant your opening hand is.
I posted the druid mill deck i used for Gothik on the hearthpwn forums and people posted they have had good results with it (killing it in 4 tries max).
The only real fight i was lucky on was Razuvious, where i happened to thoughtsteal a runeblade. But i don't know of any other deck that doesn't resolve around luck on this boss.